1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an apparatus and method for driving an LCD device. Embodiments of the present invention are suitable for a wide scope of applications. In particular, embodiments of the present invention are suitable for driving the LCD device such that a charging property of a pixel is improved.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) device uses a thin film transistor (TFT) as a switching element to display images. The LCD device has been widely used in such diverse areas as a personal computer, a notebook computer, and portable devices such as a mobile phone and a calling device, and a photocopy machine.
In the LCD device, gates and data lines cross each other to form pixel regions. A liquid crystal cell is provided in each pixel region. A desired image is displayed by applying a corresponding data signal to the liquid crystal cell. The TFT is formed adjacent to a crossing of the gate and data lines. The TFT switches the data signal to be applied to the liquid crystal cell in response to a gate pulse provided from the gate line.
The related art LCD device has a slow response time because the liquid crystal cell is not discharged fast enough in accordance with the data voltage. Thus, a sufficient video voltage is not supplied to the liquid crystal cell during a turn-on time of the TFT. A pre-charging method has been proposed to compensate the slow response time of the liquid crystal cell. In the pre-charging method, the liquid crystal cell is pre-charged with a prior data by overlapping gate pulses supplied to the adjacent gate lines.
FIG. 1 shows a waveform diagram illustrating a pre-charging method according to the related art. Referring to FIG. 1, gate pulses applied to adjacent gate lines GLi and GLi+1 are overlapped so that a data voltage Vdata is pre-charged in the pixel. For example, the gate pulses supplied to the adjacent gate lines GLi and GLi+1 may be overlapped by a half of a horizontal period.
However, the related art pre-charging method of FIG. 1 is not applicable to a dot or line inversion mode where the polarity of data voltage Vdata changes between vertically adjacent pixels. If the related pre-charging method is applied, the pixel is pre-charged with a data voltage of a first polarity in a pre-charge time, and is then main-charged with a data voltage of a second polarity in a main-charge time. Thus, if a modulation width of the data voltage Vdata increases, the main-charge time increases due to the opposite polarity of the pre-charged voltage. Hence, it is difficult to completely charge the pixel with the correct data voltage. Accordingly, the picture quality deteriorates.